Zeta Gundam & Transformers Made Out of Bicycle Parts (China)
According to new.gamme.com.tw, Optimus Prime stands 3 meters tall and had taken 50 days to complete. While Bumblebee is about 2 meters tall and took 60 days to complete. There was no info about the Zeta Gundam..

A 7 meters tall RX-78-2 Gundam bust made of 10,000 pots of flowers will be on display at Gundam Front Tokyo (Diver City, Odaiba, Japan) from October 28th -29th, 2012 to be part of the attraction for the upcoming 29th National Urban Greenery Fair Tokyo.